Wireless Power Transfer for Toys and Portable Devices

Powering electronic toys by replacing chargeable batteries or using wires are common technique, although these techniques are unsecure for the children. Providing an alternative source to power the toys is a pressing demand for kid safety. Transferring power to toys/portable devices wirelessly is an attractive and desirable technique due to eliminating the risks of replacing batteries or using cords for the toys. In this paper, a wireless power transfer (WPT) system is designed and built, to deliver power from a stationary source (primary coil) to a moving toy/portable device (secondary coil) via magnetic resonant coupling. The moving toy/device must be able to move freely, a novel primary coil design is proposed to cover the required space for the toys. Three-dimensional finite element analysis COMSOL software is used to investigate the magnetic flux density distribution of three different primary coil designs. The simulation results show the novel design of the primary coil that distributes the electromagnetic field uniformly at any location for the moving toy. A planar spiral PCB coil is designed as a secondary coil to provide the required power to the toys. Experiments are conducted to measure the received power by the secondary coil wirelessly and the maximum system efficiency is 4.9%. The transferred energy powers the electric motors of the car toy/portable devices.